1. Field of the Invention
The present invention generally relates to systems for managing rights of use of digital contents. There are basically two types of rights. A first type of rights relates to rights linked to conditions of numbers of uses. A second type of rights relates to time conditions linked, for example, to the use or availability times. The present invention more specifically relates to the managing of rights of use linked to time conditions. This concerns, for example, conditions of duration of each use of the digital content or conditions of cumulated duration of use of this content.
2. Discussion of the Related Art
Among examples of application of the present invention, are the managing of rights of use of video files, music files (MP3), radio or broadcasting files, etc. The rights of use or exploitation of the content managed by a system with time conditions are most often the direct rights of use, that is, the listening times of an audio digital file or the viewing time of a video sequence. Other rights of exploitation such as copy, transfer, or printing of digital data are generally managed by systems linked to number conditions rather than to time conditions. It is however not excluded for certain right management systems to use time (calendar) conditions to set a period of time during which the person entitled to the rights is allowed to copy, loan, transfer, or print the digital content.
The control of the time use conditions sets a specific problem, which is that the validity of these conditions must be verified all along the use of the digital content, which introduces an additional calculation load for the equipment exploiting the content (for example, a microcomputer, a digital television, an MP3 walkman).
FIG. 1 very schematically and partially illustrates, in the form of blocks, an example of a conventional circuit for managing time rights of a digital content. In this example, an application (block 1, APPLi) formed for example of a video file which must be processed by a digital processor 2 (PROC) and to which are associated time use conditions is considered. The time use conditions form, for example, a deadline (including date and time) of use of the video file. In a system such as illustrated in FIG. 1, the time condition to be verified is input into work register 3 (RT) which is periodically read from by a comparator 4 (COMP) and is compared to the current date (TIME) issued by processor 2 and calculated based on its clock CLK. In case the deadline is exceeded, comparator 4 generates an interrupt IT for the processor.
The simplified operation described hereabove well illustrates the constraint of periodic verification of the time condition to be verified.
Although such a constraint remains acceptable in the case of a single application to be monitored, it becomes frequent for systems of digital content exploitation (for example, computers) to simultaneously exploit several time conditions of a same digital content and/or several distinct digital contents, the respect time conditions of which must periodically be verified.
In such a case, this multiplies the time processor is occupied in order to carry out time condition verifications.